Acute haemodynamic effects of carvedilol in essential hypertension at rest and during exercise

The acute haemodynamic effect of carvedilol, a new non-selective beta-receptor blocker with vasodilating effect, was examined at rest supine and sitting and during 100 W bicycle exercise in 18 patients (mean age 44 years) with essential hypertension. Intra-arterial blood pressure and heart rate were recorded continuously. Cardiac output was measured by dye dilution (Cardiogreen). Two h after the first oral dose (12.5-25 mg) of carvedilol, blood pressure was reduced in all patients sitting at rest, from 176/110 to 153/101 mmHg (P less than 0.001), associated with a reduction in cardiac index (16%; P less than 0.001) while total peripheral resistance remained unchanged or was slightly reduced. When sitting up after 2 h supine rest two patients had hypotensive reactions (excessive blood pressure drop; cold, pale, sweating skin) which disappeared after lying down with elevation of the legs and light physical exercise. The fall in cardiac index was due to reduction both in heart rate (8%, P less than 0.001) and stroke index (9%; P less than 0.01). During exercise the reduction in cardiac output was less (6%; P less than 0.05) while a clear reduction (6%; P less than 0.01) was seen in total peripheral resistance. This acute haemodynamic response is different from that seen immediately after conventional beta-blockers when total peripheral resistance always increases.